Specific multi-drug resistance pattern in Gram positive & gram negative bacteria and their treatment

1. Specific Multi-drug
Resistance
MRSA-VRSA-ESBL-KPC
By
Dr. Sayan Chakraborty
2nd Year PGT- MD Tropical Medicine
School of Tropical Medicine, Kolkata
E-mail: dr.sayan@gmail.com

2. WHO Theme 2011

3. Antibiogram - Blood

5. Staph aureus today!!
Most common cause of skin and soft tissue
infections
MC cause of cellulitis, osteomyelitis, septic
arthritis, surgical wounds
MC cause of nosocomial infections
MC cause of health care associated endocarditis
(52%) and in IDUs (57%)
Common cause of bacteremia, foodborne
disease, implant infection, abscess etc

6. [2002]

7. MRSA
• 1959: First clinical
use of methicillin
• 1960: First
description of
MRSA
• Resistant to
penicillinase-
resistant penicillins
and all
cephalosporins
except ceftaroline

8. Worldwide prevalence of MRSA

9. Mechanism of Methicillin
Resistance
 Horizontal transfer of
genomic island
SCCmec
 Contains gene mecA
 Produces PBP2a
protein responsible
for resistance

10. Factors that Facilitate Transmission
Crowding

11. Frequent ContactCrowding
Factors that Facilitate Transmission

12. Frequent ContactCrowding
Compromised Skin
Factors that Facilitate Transmission

13. Frequent Contact
Contaminated Surfaces
and Shared Items
Crowding
Factors that Facilitate Transmission
Compromised Skin

14. Frequent Contact
Cleanliness
Crowding
Contaminated Surfaces
and Shared ItemsCompromised Skin
Factors that Facilitate Transmission

15. Contaminated Surfaces
and Shared Items
Frequent Contact
Cleanliness
Crowding
Compromised Skin
Factors that Facilitate Transmission
Antimicrobial
Use

16. Susceptible groups
Diabetics
Immunocompromised (HIV, Cancer,
Transplant, lupus)
Extended hospital stay
Indwelling catheters/ prosthetic devices
Elderly
Dialysis patients
IDUs
H/o MRSA

17. Lab Diagnosis of MRSA
The Clinical and Laboratory Standards Institute
(CLSI), CDC recommends:
Broth microdilution testing
Cefoxitin disk screen test
Latex agglutination test for PBP2a
Plate containing 6 μg/ml of oxacillin in Mueller-
Hinton agar supplemented with 4% NaCl
New FDA-approved selective chromogenic agars
can also be used for MRSA detection

18. Interpretive Criteria (MIC)
Test Susceptible Resistant
Oxacillin MIC ≤ 2 μg/ml ≥ 4 μg/ml
Cefoxitin MIC ≤ 4 μg/ml ≥ 8 μg/ml
Cefoxitin Disk
Diffusion
≥ 22 mm ≤ 21 mm

20. Treatment of MRSA
Oral therapy for Skin and soft tissue
infections:
Clindamycin 300-450 mg tid
TMP-SMX (1 or 2 ds tablets bid)
Minocycline or Doxycycline 100 mg q12h
Linezolid 600 mg bid
Tedizolid 200 mg once daily
Alternative: Tigecycline

21. Treatment of MRSA
Parenteral therapy for Serious infections
(complicated skin infections, bacteremia,
endocarditis):
Drug of choice:
Vancomycin 15-20 mg/kg q8-12h (max 2 g)
Daptomycin 6 mg/kg q24h
Alternatives:
Linezolid 600 mg q12h PO or IV
Ceftaroline 600 mg IV q12h
Tigecycline
New drug: Teixobactin (Gram +ve coverage)

22. Therapy for special settings
• Prosthetic valve endocarditis:
Vancomycin (30 mg/kg q24h, max 2g) or
Daptomycin 6 mg/kg q24h + Gentamicin 1
mg/kg q8h + Rifampin 300 mg q8h for ≥ 6 weeks
• Hematogenous osteomyelitis or Septic arthritis:
Children: 4 week course of therapy
Adults: More prolonged course
• Prosthetic joint infections:
Rifampin + Ciprofloxacin especially when the
device cannot be removed

23. VISA / VRSA
• 1997: Vancomycin
intermediate
Staph aureus
reported from
Japan
• 2002: Vancomycin
resistant Staph
aureus isolated

24. Mechanism of Resistance
VISA:
oAbnormally thick cell wall
oVancomycin trapped by abnormal peptidoglycan
cross-linking
oUnable to gain access to its target site
VRSA:
oHorizontal conjugal transfer of vanA gene from
vancomycin resistant strain of Enterococcus
faecalis
ovanA gene produces dipeptide D-Ala-D-Lac in
place of D-Ala-D-Ala to which the drug cannot
bind

25. Lab diagnosis of VRSA
CLSI-CDC recommends:
Reference broth microdilution
Agar dilution
Etest®
MicroScan® overnight and Synergies plus™
BD Phoenix™ system
Vitek2™ system
Disk diffusion
Vancomycin screen agar plate [brain heart
infusion (BHI) agar containing 6 µg/ml of
vancomycin]

26. Interpretive Criteria (MIC)
Staph aureus MIC (µg/mL)
VSSA 0.5 - 2
VISA 4 - 8
VRSA ≥ 16

27. Treatment of VRSA/VISA
Drug of Choice:
Daptomycin 6 mg/kg q24h
Alternatives:
Ceftaroline 600 mg IV q12h
Linezolid 600 mg IV or PO q12h
Tedizolid 200 mg IV or PO once daily
Dalbavancin - two IV doses : 1000 mg followed in 1 week by
500 mg
Other drugs for VISA: Quinipristin/Dalfopristine; Telavancin

28. Antibiogram - Urine

30. ESBL
• 1980s: 3rd generation
cephalosporin
introduced in
Ampicillin resistant E.
coli and K. pneumoniae
• 1983: K. ozaenae with
plasmid mediated
resistance to broad
spectrum
cephalosporins
• 1989: 1st “substantial
review” of ESBLs

31. ESBL Resistance Pattern
ESBL causes hydrolysis of
Penicillins
1st-, 2nd- and 3rd gen cephalosporins
4th gen cephalosporins (some instances)
Monobactams like Aztreonam
Fluoroquinolones
TMP-SMX
Aminoglycosides
Tetracyclines

32. ESBL producers
• Klebsiella pneumoniae, oxytoca
• E. coli
• Pseudomonas aeruginosa
• Acinetobacter baumanii
• Enterobacter cloacae and aerogenes
• Citrobacter freundii
• Proteus
• Serratia marcescens
• Providencia
• Morganella morganii

33. India > China > Rest of Asia, Latin America
Europe > USA, Canada, Australia

34. ClinMicrobiolRev.2005;18:657-
686.
Types of ESBL enzymes
SHV:
• 1st B-lactamase found in K. ozaenae Germany
1983
• Frequently found isolate
• SHV refers to sulfhydryl variable
• Repl glycine by serine @ pos 238
• most commonly found in K. pneumoniae
• SHV-2 accounts for extended spectrum
properties

35. ClinMicrobiolRev.2005;18:657-
686.
Types of ESBL enzymes
TEM:
• Most common, found in E. coli and K. pneumoniae
• 100+ TEM types derived from TEM-1 & TEM-2
• TEM-1
• 1st reported from E. coli isolate in pt named
Temoneira
• Hydrolyzes amp > carbenicillin, oxacillin, or
cephalothin
• Inhibited by clavulanic acid; inhibitor resistant TEM
present now
• First true ESBL is TEM-3
• Plasmid-mediated B-lactamase CTX-1(cefotaxime)

36. Types of ESBL enzymes
CTX-M
• greater activity against cefotaxime
• normally found in Kluyvera species
• mainly found in strains of Salmonella enterica
serovar Typhimurium and E. coli
• Associated with resistance to fluoroquinolones,
TMP-SMX, aminoglycosides and tetracyclines
• Increased incidence of uncomplicated cystitis due
to CTX-M producing E. coli among healthy
ambulatory woman
• Fosfomycin and nitrofurantoin - most reliable

37. MicrobDrugRestance.
2006;12:223-230.
B-lactamases other types
• AmpC
• Hydrolyze 3rd gen cephalosporins
• Induction of resistance during therapy
• Active against cephamycins (cefoxitin, cefotetan)
• Resistant to inhibition by clavulanic acid/b-lactamase inh
• May not exhibit resistance to FQs, TMP-SMX,
aminoglycosides, tetracyclines
• Carbapapenemases
• Metallo-B-lactamases & serine carbapenemases
• KPC-2, KPC-3, SME-2 most frequently isolated in US
• Metallo-B-lactamases most prevalent in Europe

38. ClinMicrobiolRev.2005;18:657-
686.
ESBL Other Types
• OXA
• Hydrolyze Oxacillin
• Predominately occur in Pseudomonas aeruginosa and
Acinetobacter baumanii
confers greater resistance to cefotaxime and cefepime
than it does resistance to ceftazidime
• PER
• Hydrolyze pcn and ceph
• VEB-1
• High level resistance to ceftaz, cefotaxime, & aztr
• GES, BES, TLA, SFO, & IBC

39. Detection of ESBLs
Disc method:
 Double disc method
 Combination Disc method
Automated methods:
• AS: Microscan, Vitek2, Phoenix
• Phenotypic tests: Etest, DDS
• Molecular tests: PCR, IsoElectric Focusing (IEF)

40. Treatment
Most reliable drugs are:
 Carbapenems
 Amikacin
 Cefepime
 Piperacillin- Tazobactam
 Polymyxins (colistin and polymyxin B)
 Tigecycline
Drugs with limited clinical data:
 Fluoroquinolones
 TMP-SMX
 Other aminoglycosides

41. Antibiogram - Sputum

43. KPC
 2001: First
reported from
North Carolina
 an Ambler class A
beta-lactamase
 Encoded by the
gene blaKPC
 Resistance similar
to ESBLs along
with Carbapenems

44. Worldwide distribution

45. Carbapenem Resistant
Enterobacteriaceae
Revised Ambler
Classification:
 Class A
carbapenemase: KPC,
SME, IMI, GES
 Class B metallo-beta
lactamase: NDM-1,
VIM, IMP
 Class D Beta
lactamase: OXA-48

46. Mechanism of Resistance to
Carbapenems
• Cleave beta lactam ring
• Ambler classification
Carbapenemase
• Active transport
• Augmented drug efflux
Efflux
• Prevent entry
• Huge rise of MIC
Loss of
membrane
porins

47. Mechanism of Antibiotic resistance

48. Lab Diagnosis
CLSI-CDC recommends:
 Disk diffusion or MIC testing
 Phenotyping by Modified Hodge test
Other tests include:
 Inhibition testing by boronic acid (class A), EDTA
(class B) or dipicolinic acid (class B)
 Nested arbitary PCR (ARB-PCR)
 Matrix-assisted laser desorption ionization-
time of flight mass spectrometry
(MALDI-TOF MS)

49. Treatment
Recommended:
 Polymyxins (Polymyxin B or Colistin)
 Tigecycline (low conc in blood and urine)
Other options:
 Fosfomycin
 Nitrofurantoin
 Aminogycosides
Newer drugs under development:
• Beta lactamase inhibitorNXL104
• Polymyxin derivatives NAB739 and NAB740
• Tetracycline PTK-0796
• Aminoglycoside ACHN-490

50. Urine C/S – Take that!!!!

51. Prevention of Resistance in
CCU
Creation of institution based strategy
for combating drug resistance
 Re-evaluation of antibiotic therapy
after 48 hours of initiation
 Adequate duration of therapy

52. CLINICAL
SCENARIO

53. Scenario 1
•40 year old female patient presented
with uncontrolled T2DM admitted for
evaluation. Although asymptomatic,
her urine C/S shows ESBL E.coli .
What to do????

54. Scenario 2
• 50 year old male admitted at CCU for acute
exacerbation of COPD along with fever.
Empirically, he was started with Inj Meropenem
(keeping in mind of his antibiotic history).
Sputum C/S was sent before starting antibiotic,
which in 3 days showed Klebsiella pneumoniae
sensitive to Ciprofloxacin, Polymixin B, Colistin
and Tigecycline (all with MIC values 0.5) and
resistant to Meropenem.
Opinion????

55. Thank
All is not lost till… the fight goes
on….